Extremely high server load!

I have about 5-6 user accounts on my server, one of them is quite....busy account.
However, I don't think the server load should be that high.
I get a 40% Cpu usage, and 80% Memory usage from time to time, meaning that CPU is always at RED lights and memory and Yellow.

I have made some optimizations on the /etc/my.cnf file , which I found in a thread in this site, but still I get huge server loads.

Is there any way I can find what exactly is causing it? like....which page, which user , etc?
I'm posting my system configuration below:

I have about 5-6 user accounts on my server, one of them is quite....busy account.
However, I don't think the server load should be that high.
I get a 40% Cpu usage, and 80% Memory usage from time to time, meaning that CPU is always at RED lights and memory and Yellow.

I have made some optimizations on the /etc/my.cnf file , which I found in a thread in this site, but still I get huge server loads.

Is there any way I can find what exactly is causing it? like....which page, which user , etc?
I'm posting my system configuration below: